3 NANO TECHNOLOGYA basic definition: Nanotechnology is the engineering of functional systems at the molecular scale. This covers both current work and concepts that are more advanced.In its original sense, 'nanotechnology' refers to the projected ability to construct items from the bottom up, using techniques and tools being developed today to make complete, high performance products.

4 HISTORY~ 2000 Years Ago – Sulfide nanocrystals used by Greeks and Romans to dye hair~ 1000 Years Ago (Middle Ages) – Gold nanoparticles of different sizes used to produce different colors in stained glass windows1959 – “There is plenty of room at the bottom” by R. Feynman1974 – “Nanotechnology” - Taniguchi uses the term nanotechnology for the first time1981 – IBM develops Scanning Tunneling Microscope1985 – “Buckyball” - Scientists at Rice University and University of Sussex discover C601986 – “Engines of Creation” - First book on nanotechnology by K. Eric Drexler. Atomic Force Microscope invented by Binnig, Quate and Gerbe1989 – IBM logo made with individual atoms1991 – Carbon nanotube discovered by S. Iijima1999 – “Nanomedicine” – 1st nanomedicine book by R. Freitas2000 – “National Nanotechnology Initiative” launched

5 K. Eric Drexler (right) popularized the word 'nanotechnology' in the 1980's.he was talking about building machines on the scale of molecules, a few nanometers wide—motors, robot arms, and even whole computers, far smaller than a cell. The U.S. National Nanotechnology Initiative was created to fund this kind of nanotech: their definition includes anything smaller than 100 nanometers with novel properties.I want to build a billion tiny factories, models of each other, which are manufacturing simultaneously. . . The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big. — Richard Feynman, Nobel Prize winner in physics.

6 FOUR GENERATIONMihail (Mike) Roco of the U.S. National Nanotechnology Initiative has described four generations of nanotechnology development (see chart below):-

7 CARBON NANO TUBESCarbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 28,000,000:1,which is significantly larger than any other material.They exhibit extraordinary strength and unique electrical properties, and are efficient thermal conductors. Their final usage, however, may be limited by their potential toxicity.Carbon nanotubes are among the amazing objects that science sometimes creates by accident, without meaning to, but that will likely revolutionize the technological landscape of the century ahead.

8 Carbon nanotubesCarbon nanotubes are fullerene-related structures which consist of graphene cylinders closed at either end with caps containing pentagonal rings.Discovered in 1991 by the Japanese electron microscopist Sumio Iijima.Nanotubes could be produced in bulk quantities by varying the arc-evaporation conditions.

9 Structure of Carbon Nanotubes Single-Wall Nanotubes SWNTsThe (n,m) nanotube naming scheme can be thought of as a vector (Ch) in an infinite graphene sheet that describes how to "roll up" the graphene sheet to make the nanotube. T denotes the tube axis, and a1 and a2 are the unit vectors of graphene in real space.Most single-walled nanotubes (SWNT) have a diameter of close to 1 nanometer, with a tube length that can be many millions of times longer. The structure of a SWNT can be conceptualized by wrapping a one-atom-thick layer of graphite called graphene into a seamless cylinder. The way the graphene sheet is wrapped is represented by a pair of indices (n,m) called the chiral vector. The integers n and m denote the number of unit vectors along two directions in the honeycomb crystal lattice of graphene. If m = 0, the nanotubes are called "zigzag". If n = m, the nanotubes are called "armchair". Otherwise, they are called "chiral".

10 Multiwall Nanotubes MWNTMulti-walled nanotubes (MWNT) consist of multiple rolled layers (concentric tubes) of graphite;In the Russian Doll , sheets of graphite are arranged in concentric cylinders;In the Parchment model, a single sheet of graphite is rolled in around itself, resembling a scroll of parchment or a rolled newspaper. (3.3 Å);Fig. 3.5 (longitudinal view) of a concentric multiwall carbon nanotube (c-MWNT) prepared by electric arc. In insert, sketch of the Russian-doll-like display of graphenes

14 Nanoscale Devices and Integrated NanosystemsNanochipCurrently available microprocessors use resolutions as small as 32 nmHouses up to a billion transistors in a single chipMEMS based nanochips have future capability of 2 nm cell leading to 1TB memory per chipNanoelectromechanical System (NEMS) SensorsA MEMS based nanochip– Nanochip Inc., 2006NEMS technology enables creation of ultra small and highly sensitive sensors for various applicationsThe NEMS force sensor shown in the figure is applicable in pathogenic bacteria detectionA NEMS bacteria sensor– Nano Lett., 2006, DOI: /nl060275y

17 ConclusionNanotechnology, Nano structures and engineered nano structures have wide applications in various fields. Many researches are going on featuring the usage of nano in various fields which are resulting in providing great results that one had never imagined of few years ago. If such sort of areas of concern are overridden the field of nanotechnology would lead in creating a world which includes the best goods that one had never imagined when so ever.